This invention relates to joint structures for coupling or interconnecting one member with another, and it relates more particularly to a joint that accommodates limited displacements between relatively movable members joined thereby. A specific environmental use for the joint is in the building industry to join concrete slabs in a manner permitting relative displacements thereof such as those induced by thermal expansions and contractions and by seismic disturbances.
It is common in erection or construction of relatively large components to provide for at least limited relative movement therebetween so as to prevent damage to such components should relative movement therebetween occur. This is especially true where such components or members are concrete slabs or similar structures because concrete is usually exposed to the elements and therefore experiences considerable thermally induced expansion and contraction of substantial magnitude. Further, in certain areas seismic disturbances enforce relative movements between such members, and when concrete is supported either directly or indirectly upon certain soils, it may be caused to shift position or "heave" as the soil expands and contracts as a result of changes in the moisture content thereof.
Typical instances of environments in which accommodation is generally provided for relative movements between adjacent structural members are concrete sidewalks, roadways and highways, concrete floorings of large-area buildings, and the plaza areas about multiple-story commercial and residential buildings of the type often referred to as "high-rise" buildings. In each of these settings, the relatively movable members, which are usually of concrete composition, are also subjected to considerable wear and abrasion, to moisture, and to impact especially from shoe heels of those walking over the surfaces and from vehicles when the surfaces are used at least in part for vehicle travel or passage. Further, as respects the plaza areas about high-rise buildings, the area underlying such plazas often provide vehicle and other storage areas, supply rooms, machinery compartments, etc., and the covering thereabove must be moisture and dirt impervious so as to prevent ingress of such materials into the room spaces.
Since the problem of interconnecting concrete slabs and the like so as to accommodate relative movements therebetween is one that is old and well known, various joint structures have been proposed and are in use for this purpose. None, however, provide a satisfactory solution to the problem of joining such relatively movable members, and among the disadvantages are the expense of such joints, the complexity thereof, the difficulty of repairing the same when it is necessary, and the corresponding difficulty of replacing a section of the joint should replacement be required. In addition, many of the joints are not dirt and water impervious, they do not withstand impact well, and they do not define a relatively uniform surface with the members that they interconnect. It is, accordingly, an object of the present invention to provide an improved joint structure of the type described which overcomes such disadvantages.
Further objects, among others, of the present invention are to provide an improved expansion-contraction joint (the term "expansion-contraction" being used in a general or generic sense to include relative displacements of all types irrespective of how induced) of the type described which is susceptible of being used in a great many environments and at various orientations including a horizontal disposition; that is able to accommodate multiple-directional movements including transverse displacements of the interconnected members toward and away from each other, limited longitudinal displacements of such members, limited vertical displacements of such members, and complex or twisting type displacements such as those that might result from a combination of transverse, longitudinal, and/or vertical displacements of the interconnected members; that requires no relative sliding movements that are susceptible of frictional inhibition and other binding-type interferences; that is able to accommodate a relatively large displacement without changing its dimension appreciably, thereby tending to maintain a relatively uniform surface with the members joined thereby; that is substantially moisture and dirt impervious and is able to withstand abrasion, impact, and other deleterious actions thereon; that is relatively inexpensive and also relatively easy to repair and/or replace whenever necessary, and that is susceptible of providing a joint having substantially any desired transverse dimension or width, and that can be provided in any length necessary and joined one to another in longitudinal succession.
Additional objects and advantages of the invention, especially as concerns particular features and characteristics thereof, will become apparent as the specification continues.